This relates generally to imaging systems, and more particularly, to imaging systems with backside illuminated near infrared image pixels.
Modern electronic devices such a cellular telephones, cameras, and computers often use digital image sensors. Imagers (i.e., image sensors) often include a two-dimensional array of image sensing pixels. Each pixel typically includes a photosensor such as a photodiode that receives incident photons (light) and converts the photons into electrical signals.
In some situations, it is desirable to capture images using infrared light in addition to or separately from, images captured using visible light. However, typical image pixels that are formed in a silicon substrate can have limited infrared imaging capability due to the relatively low absorption of near-infrared (NIR) light in silicon. Additionally, NIR photons penetrate deeper into a silicon substrate and can generate pixel crosstalk which results in lower image sharpness in existing sensors in response to NIR light.
It would therefore be desirable to be able to provide improved imaging systems for capturing infrared images.